繁殖母猪、哺乳仔猪的绝食代谢研究

利用呼吸测热器对5头繁殖母猪及其哺乳仔猪进行了绝食代谢的测定。母猪分妊娠前期、妊娠后期、哺乳前期、哺乳后期和空怀期;仔猪分哺乳前期和哺乳后期。母猪5期的绝食代谢产热量分别为100.6、92.0、105.6、109.6和79.6千卡/公斤~(0.75)·天;耗O_2量分别为20.8、20.4、22.5、23.2和16.9升/公斤~(0.75)·天;CO_2产生量分别为14.7、14.1、16.0、16.6和11.9升/公斤~(0.75)·天;呼吸商变化范围在0.66-0.72之间。仔猪哺乳前期和哺乳后期的绝食代谢产热量分别为124和112千卡/公斤~(0.75)·天;耗O_2量分别为25.8和23.4升/公斤~(0.75)·天;CO_2产生量分别为17.1和17.5升/公斤~(0.75)·天;呼吸商在0.66-0.75之间;其体蛋白分解量分别为3.4和3.3克/公斤~(0.75)·天。结果与国外有关报导相近。     

生长育肥猪绝食代谢试验的绝食时间的探讨

为探讨生长育肥猪绝食代谢试验的绝食时间,对3头瘦肉型去势公猪进行了两个体重阶段(40—50公斤)和(65—75公斤)1—6天的绝食代谢测定。前期绝食3天、后期绝食4天,呼吸商、体物质分解量和绝食产热量均达到平稳状态。分别为0.68—0.77、9.42—10.83(克/公斤~(0.75)·天)和80.50—94.17(千卡/公斤~(0.75)·天)。     

不同海拔高度下生长牦牛绝食代谢的研究

用闭路循环式呼吸面具,分别在海拔高度2261m和4272m处的暖季对绝食5—7天的生长阉牦牛绝食产热(FHP)进行测定,并在海拔高度3250m处的冬、暖两季,测定不同气温下试牛的FHP。用Brouwer(1965)的简化式计算产热量。结果表明:①在海拔2261m和4272m处,1、2、3岁牦牛的FHP(kJ/kgw~(0.75)·日)分别为351.544±25.744,305.344±20.920,298.583±17.910,和376.225±23.518,324.787±46.208,281.144±24.410。二者差异不显著(P>0.05),其方程为FHP(kJ/日)=920w~(0.52),n=25,r=0.8469。②环境气温显著影响FHP。当气温为8—15℃时,FHP相对恒定P>0.1);高于15℃时,每升高1℃,FHP(kJ/kgw~(0.52)·日)增加10.5(P<0.05);低于8℃时,每下降1℃,FHP减少14.6(P<0.05);低于-20℃时,每下降1℃,FHP增加18.4(P<0.05)。试验指出:①牦牛较低的FHP及它在不同海拔高度FHP的恒定性,是其适应青藏高原缺氧环境及冬春缺草环境的特点;它奇特的自我保护功能是适应严寒环境的特点,这些特点是长期自然选择的结果。②在高海拔地区世代生活的家畜,其代谢值低,而且在其适应的海拔高度范围内相对恒定;未获得遗传性适应的家畜,其代谢值随海拔高度的升高而升高。③生长牦牛代谢体重为w~(0.52)。     

夏季养猪防暑降温措施

<正>1各种猪适宜的温度范围1.1育肥猪:15℃~23℃(前期20℃~30℃、后期15℃~20℃。)1.2哺乳母猪:16℃~23℃。1.3种公猪:13℃~19℃。育肥猪在不同的生长阶段因体重不同,最适宜的温度是不同的,具体计算公式为:T=26-0.06W。T代表生长所需的最适宜温度,W代表猪的体重(千克)。例:猪体重为100千克时,最适宜的温度为:T=26-0.06*100=26-6=20℃。在适宜的温度范围里,猪感觉舒适,生命力较强,而且生产力     

青年尼里-拉菲母水牛绝食代谢的研究

用传统开路式牛用呼吸面具对青年尼里-拉菲水牛绝食产热(fasting heat production,FHP)进行研究.结果表明:青年尼里-拉菲水牛平均FHP为301.28 kJ/kgW0.75.d,绝食期间试牛的混合RQ(呼吸商)值平均为0.69,非蛋白分解RQ值平均为0.59,蛋白质分解RQ值很稳定为0.81,试牛平均每天排出内源尿氮(EUN)为39.54g,蛋白分解产热占总产热量平均为17.70%.     

用食道瘘管测定放牧绵羊日采食牧草干物质量

采用食道瘘管技术与两级离体消化试验及外源指示剂Cr_2O_3测定日排粪量技术3结合的方法,在新疆南山夏秋两季牧场分别进行放牧中国美利奴细毛绵羊牧草干物质采食量的测定。测得夏牧场上18只放牧母羊采食牧草干物质量平均为96.02±7.408克/体重公斤~(0.75)和日排粪干物质量平均为38.72±4.20克/体重公斤~(0.75)。秋牧场上8只放牧母羊采食牧草干物质量平均为75.41±5.799克/体重公斤~(0.75)和日排粪干物质量为38.31±2.73克/体重公斤(0.75)。测得用3只食道瘘管羊采集夏秋牧场上牧草标样的干物质消化率分别为59.65±2.376％与49.02±5.538％,秋季采食牧草干物质量及消化率均显著大于秋季(p<0.001)。两季牧场的日排粪干物质量没有显著性差异(p>0.05)。     

乳肉兼用水牛不同生长阶段绝食代谢的研究

用传统开路式牛用呼吸面具对12,18和24月龄乳肉兼用水牛绝食产热(FHP)进行研究。结果表明:12,18和24月龄乳肉兼用水牛FHP分别为334.03,328.55和306.01KJ/(kgW0.75·d);每天每头排出内源尿氮(EUN)分别为31.06,35.62和39.66g;单位代谢体重每天排出EUN分别为0.53,0.50和0.48g;蛋白分解产热占总产热量分别为17.99%,17.35%和17.98%;EUN与FHP比值分别为1.60,1.54和1.60mg/KJ。乳肉兼用生长水牛维持净能需要量:NEm=402.152KJ/(kgW0.75·d)。绝食代谢与体重指数关系为:FHP[KJ/(kgW0.75·d)]=877.864W0.57,(n=15,r=0.7075)。乳肉兼用生长水牛代谢体重为W0.57kg。     

妊娠期云南半细毛羊能量需要量

本试验旨在研究妊娠期云南半细毛羊的能量需要量。选取30只体重相近的妊娠期云南半细毛羊,随机分为5组,每组6个重复,每个重复1只羊。在不同饲粮代谢能(ME)水平(妊娠前期、中期分别为7.41、8.43、9.06、9.44和10.07 MJ/kg,妊娠后期分别为7.42、8.37、9.02、9.43和9.98 MJ/kg)下,通过饲养试验、消化代谢试验、气体代谢试验相结合的研究方法,探究妊娠期云南半细毛羊的能量代谢规律以及能量需要量。结果表明:云南半细毛羊妊娠期的ME需要量与代谢体重(W_(0.75))和平均日增重(ADG)间的关系为:妊娠前期,ME (kJ/d)=373.304W_(0.75)+19. 579ADG (R~2=0. 971);妊娠中期,ME (kJ/d)=385. 711W_(0.75)+20. 725ADG(R~2=0.952);妊娠后期,ME(kg/d)=425.267W_(0.75)+26.693ADG (R~2=0.952)。由以上回归方程可知,云南半细毛羊妊娠前期、中期和后期的维持代谢能(MEm)需要量分别为373. 304、385.711和425.267 kJ/kg W_(0.75)。妊娠前期、中期和后期云南半细毛羊每100 g日增重的ME需要量分别为1 957.9、2 072.5和2 669.3 kJ。产热量(HP)与代谢能采食量(MEI)间符合对数模型:妊娠前期,lgHP=0.000 3MEI+2.449 3 (R~2=0.691 8);妊娠中期,lgHP=0.000 2MEI+2.482 2(R~2=0.674 8);妊娠后期:lgHP=0.000 2MEI+2.530 6 (R~2=0.673 0)。因此,妊娠前期、中期和后期云南半细毛羊维持净能(NEm)需要量分别为281.38、303.53和339.31 kJ/kg W_(0.75),代谢能用于维持的效率(Km,Km=NEm/MEm)分别为0.754、0.787、0.798。     

湖羊妊娠期维持代谢能需要量的测定

应用呼吸面具测热法测定湖羊妊娠期4个阶段(即0—60天,61—90天,91—120天与121—147天)每日产热量(HP),并用消化代谢试验测出不同阶段每日代谢能采食量(MEI),将测得数据,套入Lofgreen(1968)曲线回归方程,然后推算妊娠期4个阶段的每日维持代谢能需要量(千焦耳/W~(0.75)公斤)依次为432.58、437.52、461.70与458.40。本研究阐明妊娠后期的维持需要(MEM/W~(0.75)公斤)较妊娠前期为多,符合妊娠母畜能量代谢的生理变化规律。     

黑白花生长母牛绝食代谢和不同运动量的能量代谢研究

为了研究我国黑白花生长母牛的能量代谢规律和探讨运动对奶牛能量代谢的影响,笔者用传统开路式面具装置对6、9、12、15、18月龄(各3头)的青年母牛在中立温度区内进行了绝食代谢试验,并对3头22月龄青年母牛运动状态下的产热量进行了测定。结果表明,黑白花青年母牛中立温度区内的绝食代谢产热量FHP(kcal/24hr)=277.5w~(0.653);不同速度水平行走的能量消耗分别为0.3316±0.0101cal/kgm(V=0.95±0.04米/秒)和0.4625±0.0462cal/kgm(V=1.54±0.03米/秒)。     

Hyaluronidase shortens levobupivacaine lumbosacral epidural anaesthesia in dogs

Objectives : The aim of this study was to evaluate the effects of hyaluronidase added to levobupivacaine in lumbosacral epidural blockade in dogs. Methods : Six adult mixed breed dogs (two males and four females) weighing 7 to 14 kg (10·5 ±1·5 kg) and aged two to five years were used. Each dog received both treatments in random order: levobupivacaine alone (LBA; n=6) or levobupivacaine plus hyaluronidase (LBH; n=6) administered in the lumbosacral epidural space. Systemic effects, spread and duration of anaesthesia and motor block were determined before treatment and at predetermined intervals. Results : The duration of local anaesthesia was 90 ±10 minutes (P=0·001) for LBH treatment and 150 ±15 minutes for LBA treatment. In the LBH treatment, anaesthesia reached the T12 to T13 dermatome and in the LBA treatment it reached the T11 to T12 dermatome in all animals in 5 and 15 minutes, respectively. Complete motor blockade was 75 ±12 minutes (P=0·01) and 120 ±15 minutes for LBH and LBA treatments, respectively. Clinical Significance : Hyaluronidase added to levobupivacaine significantly shortens the duration of epidural anaesthesia with the same dermatome spread into the epidural space in dogs.     

美国王鸽能量代谢的研究

本文研究美国王鸽的代谢率、每日代谢能消耗及食物能量摄入与利用,其结果:在同温条件下,1～5日龄时的代谢率(2.657±1.078meo_2/W~(0.67)·hr)为最低,6～10日龄(11.334±2.421)为最高,以后逐渐下降,至26～30日龄接近于成鸽水平。每日代谢能消耗以1～5日龄(17.971±11.147千焦/只·日)为最低,16～20日龄时为(268.490±57.124)最高,但仍低于成鸽(285.426±71.835)。在12～25℃环境中,21℃与25℃的代谢率没有显著差异,而12℃和16℃的代谢率与25℃的差异极显著或显著。10日龄前雏鸽的代谢率与体重呈强的线性正相关,而后呈强的线性负相关,代谢率呈两个相反趋向的年龄相。40～50日龄童鸽的能量摄入为 533.331千焦/只·日,真同化率为84.69％,每日代谢能消耗占真可代谢能的54.5％,大于生长能量(45.5％)。     

Animal-Driven Rotational Grazing Patterns on Seasonally Grazed New Mexico Rangeland

Global positioning system (GPS) data collected over a 4-yr period on 52 crossbred young cows grazing a 146-ha pasture were used to determine whether cattle establish patch-scale rotational patterns within pastures. Cow positions at 5-min intervals were recorded during 20 d in late winter/early spring. Estimated per capita forage allowance (PCFA) was 347 kg herbage · cow^-1, 438 kg herbage · cow^-1, 1 104 kg herbage · cow^-1, and 1 884 kg herbage · cow^-1 in 2004, 2005, 2006, and 2007, respectively. Cumulative winter/early spring precipitation (CPPT) was low in 2004 and 2006 (35 mm and 30 mm, respectively) and high in 2005 and 2007 (119 mm and 112 mm, respectively). Structured query language codes developed for this study were used to 1) select grazing GPS points with movement velocities between 1 m · min^-1 and 20 m · min^-1, 2) overlay location data on a pasture map subdivided into 30 × 30 m pixels, and 3) calculate percentage of grazed pixels (% GP), pixel residence time (RT), revisit rate (RR), and return interval (RI) for each animal. Cows grazed 31% ± 5.9 SEM of all pixels for 21 min ± 3.7 SEM, visited grazed pixels 1.6 times ± 0.18 SEM, and returned to grazed pixels after 5 D ± 2 SEM. As PCFA increased, % GP decreased (r = -0.42) and RI increased (r = 0.73) significantly (P < 0.01); however, RT decreased (r = -0.46) and RR increased (r = 0.6) significantly (P < 0.01) with increasing CPPT. Pixel attributes (elevation, aspect, slope, percentage of tree cover, and distance from water, roads, and fences) failed to explain variation in pixel RT (R² = 0.28) regardless of PCFA. The same predictors explained most of the variation in pixel RR and RI when PCFA was high (R² = 0.86 and R² = 00.76, respectively). Cows appear to establish their own patch-scale rotational patterns within pastures. Nonforage pixel attributes appear to have a strong influence on such patterns.     

Energy utilization in mature ewes from seven breeds with diverse production potentials

Effects of genetic changes in reproduction, growth, body composition or lactation on the efficiency of market lamb production depend partly on the associated changes in feed intake requirements for maintenance and for protein and fat deposition. To evaluate these relationships, feed intake and body weight changes were monitored for six pairs of open, dry, mature ewes from each of seven diverse breeds fed pelleted alfalfa (53% TDN) ad libitum (AL) or restricted (MN) to 64% of ad libitum levels, for an average of 41 d. After a 56-h fast, heat production (FHP) was measured calorimetrically for 16 h before slaughter and analysis of empty body composition. The estimated daily metabolizable energy intake/kg(.75) of body weight for no change in body energy (MEm) was 167 kcal for the AL vs 147 kcal for MN ewes, and ranged from 139 to 169 among breeds (P less than .05). Estimated above-maintenance ME requirements, kcal/g tissue deposited, were 30 to 50 for protein and 10 to 14 for fat deposition. Mean FHP/d, adjusted by regression to zero activity, was 72 kcal/kg(.75) weight and was nonsignificantly higher (3.3) for the leaner MN than for AL ewes. Thus, the lower total MEm for MN than for AL ewes was necessarily derived from reduced metabolic and physical activity and(or) higher digestibility. Genetic increases in lean vs fat deposition would reduce above-maintenance feed by one-third to one-fourth because of the high water content of lean, but more lean mass may increase maintenance costs.     

Magnetic Resonance Imaging (MRI) Spinal Cord and Canal Measurements in Normal Dogs

The goal of this study was to establish Magnetic resonance imaging (MRI) reference ranges for spinal measurements in normal dogs. Forty dogs (1–10 kg, 11–20 kg, 21–30 kg, > 30 kg; 10 dogs per category) underwent spinal MRI. Measurements were performed on sagittal T2‐W images at the level of the 4th thoracic vertebra (T4), the 9th thoracic vertebra (T9) and the 3rd lumbar vertebra (L3). Spinal canal diameter (mm) ranged from 6.07 ± 0.63 (1–10 kg) to 8.27 ± 1.15 (> 30 kg) at the level of T4; 6.55 ± 0.61 (1–10 kg) to 9.04 ± 1.26 (> 30 kg) at the level of T9; and 6.80 (6.47–7.00; 1–10 kg) to 9.00 (7.90–9.73; > 30 kg) at the level of L3. There were significant differences (P < 0.05) in spinal canal diameter between groups. Mean spinal cord diameter (mm) ranged from 4.46 ± 0.51 (11–20 kg) to 4.70 ± 0.35 (1–10 kg) at the level of T4; 4.41 ± 0.50 (> 30 kg) to 4.85 ± 0.57 (1–10 kg) at the level of T9; and 4.52 ± 0.51 (> 30 kg) to 5.14 ± 0.68 (1–10 kg) at the level of L3. There were no significant differences in spinal cord diameter between groups. Spinal cord‐to‐spinal canal ratio varied significantly, ranging from 0.51 ± 0.08 (> 30 kg at L3) to 0.78 (0.69–0.80; 1–10 kg at T4) (P < 0.05). These findings are important when using MRI to evaluate patients with suspected diffuse spinal cord disease.     

湖羊和考力代羊公羔垂体－性腺轴系内分泌活动的差异

用放射免疫方法测定了湖羊和考力代羊公羔从初生到１８０日龄垂体内ＬＨ总量，血浆ＬＨ和睾酮浓度的变化。结果表明：湖羊从初生到９０日龄垂体内ＬＨ总量迅速上升（Ｐ＜０．０１），以后呈下降趋势；血浆ＬＨ浓度０～２０日龄较低（０．８９～１．０３ｍＩｕ／ｍｌ），３０日龄开始上升，９０日龄达到峰值（２．３４ｍＩＵ／ｍｌ），以后呈下降趋势。血浆睾酮从４０日龄起迅速上升，１２０日龄达到２．７３ｎｇ／ｍｌ，以后维持于高水平（２．３４～４．４４ｎｇ／ｍｌ）。考力代羊０～１８０日龄垂体内ＬＨ总量呈持续上升趋势（Ｐ＜０．０１），血浆ＬＨ水平０～８０日龄维持较低水平（０．５２±０．９９ｍＩｕ／ｍｌ），以后呈上升趋势；血浆睾酮水平０～１３０日龄很低（０．１９～１．１３ｎｇ／ｍｌ），１４０日龄开始上升。两品种比较，０～９０日龄湖羊垂体内的ＬＨ总量，血浆ＬＨ及睾酮水平均高于考力代羊。提示湖羊公羔性成熟早与其生后早期垂体合成和释放ＬＨ水平高有关。     

A calorimetric estimate of the efficiency of utilisation of dietary energy by the growing cockerel

The metabolic rates of four growing cockerels, aged between 10 and 18 weeks, were measured using respiration calorimetry. Measurements were made when the birds had been fasted for 48–72 h and when they had been given a cereal‐type diet at maintenance and production levels.

The mean fasting heat production (±SE) was 92.3 (±5.0) kcal/kg d or 113.4 (±5.7) kcal/kg3/4 d. The relationship between energy balance (T) and ME intake (X) was calculated to be Y = 0.851X—92.9 indicating that the maintenance ME requirement was 109.1 kcal/kg d and that the net availability of the ME was 85.1 per cent. The efficiency of energy utilisation in relation to plane of nutrition and to the amount of protein and fat deposited is discussed.     

杀螨剂“克螨特”亚致死剂量对朱砂叶螨实验种群生命参数的影响

为了科学合理地使用桑园杀虫剂,采用Jackkn ife统计推断技术,在16 L、(30±1)℃、RH 75%±10%,8D、(20±1)℃、RH 65%±15%的条件下,对寄主为桑树的朱砂叶螨种群水平上的亚致死效应进行了研究。朱砂叶螨成螨经杀螨剂“克螨特”亚致死剂量(60.83 mg/L)处理后,成螨寿命降低,雌螨总产卵量显著低于对照组;处理组内禀增长率(0.272 0±0.007 5)也显著低于对照组(0.338 6±0.005 5)。     

采用英系北京鸭评定棉籽粕净能的研究

本研究旨在评定棉籽粕在英系北京鸭上的净能(NE),并运用棉籽粕的表观代谢能(AME)和常规成分建立其预测方程。根据析因法将棉籽粕替代饲粮的NE剖分为维持净能(NEm)和生产净能(NEp),利用回归法测定NEm,比较屠宰法测定NEp,再套算得到棉籽粕的NE。选取400只7日龄的英系北京鸭进行动物试验。首先选取20只肉鸭在试验开始时挫颈致死,测定其体能量作为测定NEm和NEp的共同初始能量对照;再选取50只肉鸭用于NEm的测定,NEm用禁食产热(FHP)估计,共设5个组(每组5个重复,每个重复2只),分别为自由采食组及限饲15%、25%、35%、45%组,均饲喂基础饲粮1;剩余的330只肉鸭用于NEp的测定,共设33个组(每组5个重复,每个重复2只),分别饲喂基础饲粮2和以不同棉籽粕替代15%基础饲粮2的试验饲粮。于14日龄时将所有的试鸭挫颈致死,测定所有试鸭的体能量。最后,将实测棉籽粕NE与AME和其常规成分进行相关分析和多元逐步线性回归分析建立棉籽粕NE的预测方程。结果显示:英系北京鸭的FHP为580.7 k J/(kg BW0.75·d),棉籽粕替代饲粮提供给肉鸭的NEm和NEp分别为(2.97±0.15)MJ/kg和(5.22±0.12)MJ/kg,棉籽粕替代饲粮提供给肉鸭的NE为(8.19±0.09)MJ/kg,计算得到的棉籽粕的NE和AME分别为(6.12±0.62)MJ/kg和(10.05±1.02)MJ/kg,AME转化为NE的效率为(60.97±2.04)%,使用AME和常规成分建立棉籽粕NE的最佳预测方程为NE=3.276+0.241AME+0.044CP-0.081ADF[决定系数(R2)=0.954,残余标准差(RSD)=0.13 M J/kg,P0.01],式中CP为粗蛋白质,ADF为酸性洗涤纤维。由以上结果可知:英系北京鸭棉籽粕的NE为(6.12±0.62)MJ/kg,分布范围为5.04~7.30 M J/kg,变异较大;运用AM E结合常规成分可以准确预测英系北京鸭棉籽粕的NE。     

Performance of a station-managed N'Dama herd in the Gambia

Summary Data collected on N'Dama cattle from a Government Station at Yundum, The Gambia were analysed for a range of performance traits recorded during the period 1970 to 1985. Least squares procedures were employed to evaluate the influence of environmental and genetic effects on reproductive and productive performance traits. Mean age (n=59) and weight (n=87) at first calving were 48·2±7·6 (s.d.) months and 235±35 kg respectively and were significantly (P<0·05) affected by year of birth. Calving intervals averaged 634±32 days (n=160) but their distribution showed three peaks; 12, 24 and 33 months. Previous year of calving had a significant effect on calving interval (P<0·01). Calf mean liveweights at birth, one, three and six months and at weaning (eight months) were 20·1±3·7, 30·7±6·0, 51·1±13·2, 88·9±25·0 and 110·5±27·0 kg, respectively. Calf mean daily weight gains to weaning averaged 0·38±0·14 kg. Liveweights and growth rates were significantly influenced by year of birth (P<0·01) and sex of calf (P<0·05). Cow mean liveweights at calving and six months after parturition were 272·3±43·0 and 277·4±34·2 kg. Calf mortality from birth to weaning was 4·6%. Productivity indices based on an eight-month weaner calf per cow per year, per 100 kg cow per year and per 100 kg of metabolic weight of cow per year were 82·6±36·5, 30·5±11·9 and 138·2±55·4 kg respectively. These levels of productivity were equal or superior to those obtained for N'Dama cattle in similar management situations elsewhere in West Africa and to those of a larger breed under a ranch situation in East Africa.

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Resumen Se analizaron los datos acumulados durante el periodo 1970 a 1985, sobre el desempe?o de un hato de ganado N'Dama en una estación experimental en Yundum, Gambia, El procedimiento de mínimos cuadrados se utilizó para evaluar la influencia de efectos ambientales y genéticos sobre el rendimiento productivo y reproductivo. El promedio de edad (n=59) y peso (n=87) en la primera parición fue de 48·2±7·6 (s.d) meses y 235±35 kg, respectivamente siendo significativamente afectado por el a?o de nacimiento (P<0·05). El intervalo entre partos fue en promedio de 634±32 días (n=160) mostrando la distribución tres picos: 12, 24 y 32 meses. El a?o anterior a la parición tuvo un efecto significativo sobre el intervalo entre partos (P<0·01). Las medias de los pesos de las crías al nacimiento, al mes, a los tres y seis meses de edad y al destete (ocho meses) fueron 20·1±3·7, 30·7±6·0, 51·1±13·2, 88·9±25·0 y 110·5±27·0 kg respectivamente. La ganancia de peso media diaria hasta el destete promedió 0·38±0·14 kg. Las tasas de peso vivo y crecimiento fueron significativamente influenciadas por el a?o de nacimiento (P<0·01) y sexo de la cria (P<0·05). La media del pese corporal de las vacas a la parición y a los seis meses después de la misma fue de 272·3±43·0 y 277·4±34·2 kg. La mortalidad desde el nacimiento hasta el destete fue de 4·6% Los indices productivos basados sobre ocho meses de ternero destetado por vaca por a?o, por 100 kg por vaca por a?o y por 100 kg de peso metabólico por vaca por a?o fueron 82·6±36·5, 30·5±11·9 y 138·2±55·4 kg, respectivamente. Estos niveles de productividad fueron iguales o superiores a aquellos encontrados en ganado D'Dama en condiciones similares de manejo en Africa Occidental y a aquellos de una raza más grande bajo pastoreo extensivo en Africa Oriental.

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Résumé Les données rassemblées sur le bétail N'Dama entretenu à la station de Yundum, en Gambie, ont été analysées pour une série de caractères ayant trait aux performances enregistrées de 1970 à 1975. La méthode des moindres carrés a été utilisée pour évaluer l'influence de la génétique sur les caractéristiques des performances liées à la reproduction et à la production. L'age moyen (n=59) et le poids (n=87) au premier vêlage ont été de 48,2±7,6 (d.s.) mois et 235±35 kg respectivement. Ces paramètres ont été affectés de fa?on significative par l'année de naissance. L'intervalle moyen des vêlages a été de 634±32 jours (n=160), mais leur répartition a montré trois pics à 12, 24 et 33 mois. L'année précédant le vêlage a eu un effect significatif sur l'intervalle de vělage (P<0,01). Les poids moyens des veaux à la naissance puis à un, trois et six mois et au sevrage à 8 mois ont été respectivement de 20,1±3,7, 30,7±6,0, 51,1±13,2, 88,9±25,0 et 110,5±27,0 kg. Les gains quotidiens moyens du veau jusqu'au sevrage ont été de 0,38±0,14kg. Les poids vifs et les taux de croissance ont été influencés de fa?on significative par l'année de naissance (P<0,01) et le sexe du veau (P<0,05). Les poids moyens des femelles au vêlage et 6 mois après le part ont été de 272,3±43,0 et 277,4±34,2 kg. La mortalité des veaux de la naissance jusqu'au sevrage a été de 4,6 p. 100. Les indices de productivité ont été basés: sur le sevrage du veau à 8 mois par femelle et para an; pour 100 kg de poids vif par femelle et par an; pour 100 kg de poids métabolique par femelle et par an. Les résultats ont été les suivants: 82,6±35,5 kg, 30,5±11,9 kg, 138,2±55,4 kg respectivement. Ces niveaux de productivité ont été égaux ou supérieurs à ceux obtenus pour le bétail N'Dama élevé dans des conditions identiques en d'autres régions de l'Afrique de l'Ouest et à ceux d'un élevage plus grand géré en ranching en Afrique de l'Est.